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E. I, d u Po n t d e Ne mo u r s & Co mp a n y
Wil min g t o n , De l a w ar e i989s
ENGINEERING DEPARTMENT
July 1, 1975
N, D. KRIVANEK CENTRAL RESEARCH
AND DEVELOPMENT HASKELL LABORATORY
BLOOD Pb RESPONSE TO AIR Pb
As you requested, I have analyzed data in the literature on the relationship between air Pb and blood Pb. I have concluded that:
(i) The Azar et al. data indicate that the slope of the log blood Pb - log air Pb relationship is small. For example, a 100& increase in air Pb results in a 11.2 increase in blood Pb.
(ii) The data by Azar et al. show that blood Pb will increase approximately 1 pgm/100 ml when air Pb increases 1 pgm/m3. It should be noted that the blood Pb - air Pb response curve is a loglog relationship and is not linear.
(iii) Points (i) and (ii) are based on the data reported by Azar et al. It is shown that other data in the literature are consistent with those reported by Azar et al.
A discussion of the analysis is attached* Please contact me if you have any questions.
Ef 'I SION
R. D. Snee Applied Statistics
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ANALYSIS ON THE RELATIONSHIP BETWEEN AIR Pb AND BLOOD Pb
1. Introduction
The following analysis of the relationship between air Pb and blood Pb concentrations is based on data reported in the papers listed in the References at the end of this report.
2. The Slope of the Blood Pb - Air Pb Curve is Small
The Azar(l) paper develops a log-log relation between air Pb and Blood Pb of the form
log blood Pb = 1.2257 + 0,153 log air Pb
or blood Pb = 16.82 (air Pb)0,153
Assuming the log-log model is correct, the percent increase in blood Pb which results when air Pb is increased from x* to Xg is given by
Blood Pb Increase {%) ~ 100((xg/xi)0a53-l) (2)
This relationship shows the small dependence of blood Pb on air Pb. For example, a 100# increase in air Pb (ie the air Pb doubles) results in only an 11.2# increase in blood Pb.
Blood Pb Increase \%) = 100{ (2/l)0a53-l) = 11.2#
Table 1 summarizes increase in blood Pb as a function of air Pb. From equation (2) we see that the % increase in blood Pb is dependent on the slope of the log-log equation (ie, b * 0.153). Results using the slope of the Goldsmith and Hexter line (3) (ie, B = 0.243) are also Included in Table 1 for comparative purposes* It should be noted that the Goldsmith-Hexter slope lies outside the 95# confidence limits of the Azar et al slope (0,153+0,079). Even with the larger Goldsmith and Hexter slope the % increase in blood Pb is considerably smaller than the corresponding increase in air Pb.
3. Change in Blood Pb fuam/100 ml) Resulting from a 1 uom/m3 'increase in air Pb is approximately 1 uom/lOu ml
The log-log model reported by Azar et al (reference 1, equation 1) can be used to compute the expected change in blood Pb resulting from a 1 pgm/m3 increase in air Pb. The change in blood Pb is given by
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where b is the slope of the log-log equation. The blood
Pb - air Pb response is shown in Table 2 for both the Azar et al slope (b-0.153) and the Goldsmith and Hexter slope Jb=<), 243). An examination of Table 2 indicates that, in general* a 1 ugm/m3 increase in air Pb results in a blood Pb increase of I ugm/100 ml.
The Azar et al Blood Pb - Air Fb Relationship Is the Best Available Model and Is Consistent with Results from Other Studies
The preceeding information is based on the Azar et al blood Pb - air Pb model. This model was developed from
the most comprehensive study conducted to date. The air Pb exposure for 150 subjects was determined 24 hours/day for periods of 2-4 weeks. Blood samples were obtained twice/week from each subject.
The slope of the log-log relationship reported by Azar et al, Goldsmith and Hexter, and calculated from the Albany Study are
Study Azar, et al
Goldsmith and Hexter Albany Study
Slope...(bj, 0.153
0.243
0.243
95/u Conf. Limits ,079
Given two blood Pb values and the corresponding air Pb values, the slope of the log-log model is
where air Pb* < air Pb;>. For example, the slope developed from the Albany Study is
Slope
= 0.243
Log Blood Pb - log air Pb slopes developed from data reported in references 2, 4, 5, and 6 are summarized in Table 3 and shown graphically in Figure 1. The results in Table 3 were
developed using assumed ambient air Pb concentrations of 1.2 ugm/m3 for Kehoe's subjects and 2.0 j.>gm/ms for the Williams, King and Walford and Cole to Lynam data sets. With the exception of the latter two studies the estimated slopes are in general agreement with the Azar et al slope.
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Table 1
Percent Increase in Bleed Pb as a Function of Percent Increase in Air Pb
Air Pb Ratio (x/xi )
1.10 1.25 1.50 2 3 4 -5 .10
Air Pb % Increase
10
25 50 100 200
300 400 900
% Increase in Blood Pb
6loee 0.153*
Slone = 0.243**
1.5 2.3
3.5 5.6
6.4 11.2
10.4 16.3
16.3
30.6
23.6
40.1
27.9
47.9
42.2
75.0
.* Azar et al (1) ** Goldsmith and Hexter (3)
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Table 2
Blood Pb Response (Apgm/100 ml) to a 1 p.gm/m3 Increase in Air Pb
Data Source
Current Level Air PbBlood Pb
Starke, FL***
0.64
Barksdale, WI*
1.01
Philadelphia Cab*
2.62
Los Angeles Office Wkrs.* 3.06
Los Angeles Cab*
6.10
16,4 13,6 22.4 19.9 24,6
Albany Study
3.2 26
Albany Study
10.9
35
ABlood Pb (ugm/l.00 ml) 1 ugm/m? Air Pb Increase SlopeQ,153* SlopeQ.2A3**
2,5 4.2
1.5 2.5 1,1 1.6
0.9 1.4 0.6 0.9 1.1 1.6
0.5 0,6
* Azar et al (1) ** Goldsmith and Hexter (3)
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REFERENCES
1. Azat, A., Snee, R. D. and Habibi, K, (1972). Relationship
of Community Levels of Air Lead and Indices of Lead Absorption, Proceedings of the International Symposium Environmental Health Aspects of Lead, Amsterdam, October 2-6, 1972, pp. 581-594.
2. Cole, J, F, and Lynam, D. R. (1972), ILZRO'S Research to
Define Leads1 Impact on Man. Proceedings of the International Symposium Environmental Health Aspects of Lead. Amsterdam, October 2-6, 1972.
3. Goldsmith, J. R. and Hexter, A. (1967). Respiratory Exposure to Lead: Epidemiological and Experimental DoseResponse Relationships, Science. 158. 132-134,
4. Kehoe, R. A. (i960). The metabolism of lead in man in health and disease. The Harken Lectures. 38-53.
5. Kehoe, R. A. (1966). Criteria for Human Safety from the Contamination of the -Ambient Atmosphere with lead. Proceedings of the International Congress on Occupational Health. Vienna, September 19-26, 1966, .83-98.
6. Williams, N. K., King, E., and Walford, J. (1969), An
Investigation of Lead Absorption in an Electric Accumulator
Factory with the Use of Personal Samplers, Brit J Ind Med
202-216.
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